Haiko,
In 10knts +, you would remove the spine and you have your planning board. In less than 10knts, it should sail like a serenity, a non planing hull.

Regarding Jim Drake's desin, I think it was called the mercury, similar idea but with the removable spine, you can remove all the excess weight needed with long waterline length. The main problem with hybrid boards is that at planning windspeeds, they are very heavy (think rsx and kona).

I think the question is how light would the spine be? - 6kg would be the target (9kg board + 6kg spine = 15kg longboard)
Is that possible for that shape at 110litres at a low cost/tech?
This is where I have my doubts (I think it would be more like 9kg which maybe too heavy)

Who wants to volunteer to build one?

12th January 2008 12:35 AM

crazychemical

wouldn't that be increadibly hard to sail? making a simple jibe would require all the strength in ones legs by the looks at the drawing because you have a 'backdrag' of over a meter behin you that needs turning. Though thats not realy the point in formula but still. Also in stronger winds, over 14 knots lets say with a formula sail wouldn't the speed be much lower because of the bigger surface still 'attached' to the water? Also, what i don't really get, is the spine submerged or is it really basicly a floating serenty with a formula on top? Because in that case i really don't see it working ...
also, wasn't jim drake working on a simular project, not with a spine, but with a double planning area, a sort of rsX class type of board. i saw drawings of it on the 2007 website ...

11th January 2008 10:27 PM

Joe

Agreed - but the cost of the spine could be qite low - and if it was two piece it would much easier to transport.
In reality - the ultimate olympic racing class is not formula - it is formula and serenity like you suggested with 1 sail - ie formula 12
- formula 31 = $10,000 for 8-25knots vs formula & serenity + 1 sail = $6,000 for 0-25knots vs formula & spine + 1 sail = $5,000 for 0-25knots.

11th January 2008 09:52 PM

James

Stacking a formula board on top of a Serenity. Hmm... Could be worth a try but it looks like a disaster to me.

If you have to carry both the long spine and the wide board around, and always be attaching and detaching the spine, you might as well have two, totally separate boards (formula and serenity).

That's my 2 cents.

11th January 2008 09:22 PM

Joe

Waterline Extender Idea

What do you think:
- Take a wide board 230x90+/- (or a formula board) and add a long center "spine"
- the idea is to extend the waterline length to improve the subplanning speed of the board
- the spine would be +/- 4.5m x 12"x12" (think half of a serenity) probably +/- 110litres (could be made two piece)
- the "spine" would attach to the underside of the board by the finbox (the fin would attach to the spine (with a finbox) and be connected to the board via longer bolts through the board's finbox) - and a single bolt and plate at the front of the board (2 connections)
- when sailing if the leeward side of the board was depressed, the spine should act as a long single waterline
- the spine would extend past the board approx 1 m at the front and 1 m at the back (must ensure the coe & clr line up)
- hopefully you could get the weight down fairly low (6kgs?) - no footstaps centreboard etc...

Just think of the racing class potential for this!

All you designers out there let me know - it is cold outside so it is time to let the mind wander!